Steve10

I've been doing WOT on my 165 MAF "modded ARAP". I started out adding quite a bit of fuel in the "PE % F/A vs RPM" table, and measuring with a Gtech. Many small steps later I'm adding negative numbers to this table and I'm at 12.7 WOT AFR. I should slow down or encounter much knock before I'm too lean, right? I've almost given up on reading plugs...they always look about the same color of light biege. I guess if I go too lean I'd finally see some signs on them though, right? Anyway, the car gets faster and faster the leaner I go, but something inside me doesn't want to keep inputing more negative numbers in that table. Anybody went too lean?

ski_dwn_it

Hey there partner,
If I read your post correctly I think you may have things a bit backwards, unless I am mistaken, but I don;t think so. If your at ~12 then your RICH, not lean. 14.7 is perfect and anything above that is lean, anything below that is rich. You may be right were you want to be. From what I have read, you want to be a bit rich at WOT, for several reasons including it cools your vavles. This may be one of the lesser important reasons, but nevertheless it's there. I'm sure if I am totally wrong someone will step in, but I am 99.9% positive that I am correct. Good Luck!

Grumpy

Gads, talk about not being even close!.
He was talking about WOT (Wide Open Throttle).
Run 14.7 at WOT and you'll be buying rings and exhaust valves.

14.7 is only relative to the chemical reaction, no more no less. It has NOTHING to do with best idle, cruise or WOT. BTW, the ecm AVERAGES that 14.7 to just keep the converter happy, You notice the O2 shoes rich and lean. They could easily set the ecm to maintain a much smaller swing off AFRs, but they don't.

Please don't even enfer info., as being even close to right unless your sure, gads. Engines are too expensive to just guess or miss info., about......

Grumpy

Remember your using a calculated number so there can be some variance from what the actual numbers are.

Tune for best performance, and then add a couple percent, just to be on the safe side. I'd also suggest 2d less timing for normal street use.

Silver or black flea sized turds on the porclean are death signs. So is ash white, as compared to bone white. Keeping a min of a light biege is generally good. Any gray and your borderline on detonation.

If your using a WB then bravo.
Remember calc'd numbers and oem O2 numbers are only rought estimates....

ski_dwn_it

Grumpy,
I think you misunderstood what I was saying. I was simply trying to explain to him that 14.7 was the point at which you switch from rich to lean. When I first read his post I thought he was saying "He was Lean at ~12". And I was in no way saying that he should be running at 14.7 @ WOT! I misread what he was saying and you misread what I was trying to convey to him.
I realize now after reading his post that he was refering to lean with respect to a WOT condition.
Sorry for any confusion I may have caused! But for what it is worth I think we were both trying to say the same thing.

I have a pretty good memory and I believe I read that somewere from you Grumpy.

Good Luck Tuning.

Steve10

Ski, yes I know all about ideal AFR's, cruise or WOT. Thats why I spent so much time getting my part throttle BLM's right.

Grumpy, yes understood, only calculated numbers. That's exactly what I thought, first sign of that shiny grayish appearance and I'm too lean. My experience jetting dirtbikes, is that they start bogging before you see the death sign on the plugs. I sure wish I was using a WB, that would give me more confidence. I'm .18 away from my goal of 12's so I'm satisfied with the results for now. I'm doing the LT1 intake swap in a couple of weeks...guess what...get to start all over again.

Grumpy

On a v8 you can be off enough that a couple cylinders are in death throws, and still run great for a pass or two, that why I mentioned going back rich.

For the $160 for a WB you really should invest in one if your at all serious about tuning.

Use a 8051 with the LT1.
It is really a slick pcm to work with and Tunercat has a pretty good .tdf for it. Using the Tunercat stuff you can delete the MAF and go full time MAP. Thou be sure the latest .tdf still allows that.
Gears and some tuning had a neighbors 95 Caprice running high 14 (with a stock 4020# car).

Steve10

Is that $160 WB the one I saw the thread on a little while ago. I guess I need to venture over on the other forum you mentioned. I definately need that.

Can you tell me more about the 8051? Swapping to SD is on my future mod list after seeing some guys results on this forum. What is the difference in this PCM vs doing the normal '91-92 swap? Does the fact that I'm switching to an LT1 intake justify the 8051, or would it make sense for say a Miniram owner to do the same? What would you figure the PITA level would be, harnesses, etc.? Needless to say, I'm intrigued by your suggestion and your experience with it. This intake swap will put me at the point of "no further engine mods for awhile," so tuning and getting the most out of my setup is where I'm planning to put my time and money.

leirch

I think Grumpy mistook what you meant by LT1. He must have thought an entire engine swap, not just the intake on a Gen1 SBC.

Steve10

Yeah, that makes sense.